<!DOCTYPE html>
<html>
<head>
<title>Loading...</title>
<meta charset="utf-8">
<script src="libmupdf.js"></script>
<script>
var filename = new URL(window.location.href).searchParams.get("file");
if (!filename)
	filename = "pdfref13.pdf";
Module.preRun = function () {
	FS.createPreloadedFile(".", filename, filename, true, false);
};
Module.postRun = function () {
	loadDocument(filename);
};

var currentDocument = null;
var currentPage = 1;
var currentZoom = 72;
var pageCount = 0;
function loadDocument(filename) {
	currentDocument = mupdf.openDocument(filename);
	document.title = mupdf.documentTitle(currentDocument);
	pageCount = mupdf.countPages(currentDocument);
	updatePage();
}
function updatePage() {
	document.getElementById("page").src = mupdf.drawPageAsPNG(currentDocument, currentPage, currentZoom);
	document.getElementById("pageNumber").value = currentPage;
}
function nextPage() {
	if (currentPage <= pageCount) {
		++currentPage;
		updatePage();
	}
}
function prevPage() {
	if (currentPage > 1) {
		--currentPage;
		updatePage();
	}
}
function gotoPage() {
	var page = parseInt(document.getElementById("pageNumber").value)
	if (page >= 1 && page <= pageCount) {
		currentPage = page;
		updatePage();
	}
}
function zoomIn() {
	currentZoom *= 1.2;
	updatePage();
}
function zoomOut() {
	currentZoom /= 1.2;
	updatePage();
}
</script>
<style>
body{margin:2em;background-color:#aaa}
</style>
</head>
<body>
<p>
<button onClick="prevPage()">&lt;</button>
<input id="pageNumber" onChange="gotoPage()" type="text" size="5">
<button onClick="nextPage()">&gt;</button>
<button onClick="zoomIn()">+</button>
<button onClick="zoomOut()">-</button>
<p>
<img id="page">
</body>
</html>
